Casing gauge



FIG. 1 is a side elevational view of a casing gauge showing my new design;

FIG. 2 is a side elevational view 120° to the right of the view of FIG. 1;

FIG. 3 is a side elevational view 120° to the left of the view of FIG. 1;

FIG. 4 is a bottom view;

FIG. 5 is a top plan view thereof. 

The ornamental design for a casing gauge, substantially as shown and described. 